Biomechanical Investigation of Locked Plate Fixation with Suture Augmentation in a Comminuted Three-Part Proximal Humerus Fracture Model

摘要

Background: Locked plating of displaced proximal humerus fractures is a reliable fixation method. Greater tuberosity (GT) failure is a known complication that may occur in the early post-operative period. Despite postoperative immobilization, the rotator cuff continues to exert significant forces on fracture fragments. Our hypothesis is that suture augmentation will provide greater stability of the GT than locked plating alone. To prove this we developed a three-part proximal humerus fracture model to test fracture fixation. Methods: A biomechanical study was performed on nine fresh frozen cadaveric humeri, simulating a three-part proximal humerus fracture (Neer Classification). Rotator cuff tendon insertions were preserved to physiologically load the proximal humerus. The fracture was reduced and fixed with a locked plate alone or a locked plate with suture augmentation of the GT to the rotator cuff tendons. Biomechanical testing utilized a materials testing machine and a three-dimensional motion capture system to quantify interfragmentary motion under torsional loading as a function of fixation type. Results: Greater torsional stability was observed in the suture-augmented group compared to the plate only group (p = 0.0012). There were two catastrophic failures in the plate only group while none of the suture reinforced constructs failed. Conclusions: In our model, suture-augmentation of the GT to the rotator cuff provided greater stability than locked plating alone. The current study provides a biome-chanical basis for reinforcing locked plate constructs with sutures. The added stability afforded by suture-augmentation may mitigate rotator cuff forces in the clinical setting, avoiding fracture displacement in the early postoperative rehabilitation period.